This invention relates to a filter device for the softening and/or complete desalination of a liquid, particularly water, of the type which includes a container which is filled with ion exchanger compound and through which the liquid to be treated flows, having an inflow and an outflow opening, and, within the container, a hollow filtering member, the interior of which is connected to the outflow opening, for discharging purified liquid, in general and more particularly to an improved filter device of this nature.
Filter devices with the design noted above are known in a multiplicity of embodiments and are used, for instance, in car repair shops for loading car batteries, in chemical laboratories, pharmacies, etc. so that pure water is available when needed.
In these filer devices, the filtering member is embedded in ion exchanger compound which consists of finegrain synthetic resin.
In operation of such filter devices, the ion exchanger compound is densified through the influence of the flow and the force of gravity, causing abraded particles of the filer resin to be deposited on the exposed outside of the filtering member and clog up its pores. This leads to an increase of the flow resistance and to a further increase of the development of bridges over the individual pores of the filter mantle.
The smaller the capacity of the container of such filter devices, the larger is the specific liquid throughput or the flow rate, which means that the fine-grain filter resin clogs up the pores of the filtering organ much faster, and that, thereby, the output rate such devices is reduced relatively quickly and permanently.
It is an object of the present invention to maintain, in filter devices of the type described at the outset, the flow resistance through the filter medium as low as possible over extended periods of time.